How does an IP-PBX work?
By Joel Snyder, Network World Lab Alliance If you’re thinking about jumping into the world of VoIP, one option is an on-site IP-PBX. With products ranging from freeware open source to turn-key appliances, you’ll find many alternatives for businesses of any size. The term “IP-PBX” is commonly used, but it is slightly misleading because the roles the old PBX systems and new VoIP-enabled ones are not a one-to-one match. In standard analog telephony, each phone is connected using pairs of wires to a central switch, called a PBX, which then connects to the local telephone company and long distance providers using more wires. Every call goes through the PBX and every telephony feature (such as automated attendant, call forwarding or voice mail) is a function of the PBX. In the world of VoIP telephony, the function of the PBX is more distributed. For example, once a call is set up, the actual voice traffic can go directly from one IP telephone to another IP telephone without passing through t
